The present invention relates generally to biconical antennas, and more particularly, to an improved high-power, shaped-beam, ultra-wideband biconical antenna.
A biconical antenna is used in a system that requires a 360 degree coverage in the azimuthal plane with a particular coverage in the elevation plane. Due to the frequency independent nature of its construction, the biconical antenna is well-suited for use in ultra-wideband systems. For uncorrupted transmission of time-domain waveforms, the biconical antenna must be designed such that its gain is semi-flat as a function of frequency.
The basic biconical antenna and its associated theory is described in detail in a book by J. D. Kraus entitled Antennas, published by McGraw-Hill, for example. None of the unique features of the present invention are discussed in this book. Also papers have been written on the subject of biconical antennas. However, a literature search through the IEEE Antennas and Propagation Transactions yielded no papers that described the unique features associated with the present invention.
Several companies manufacture various derivatives of the basic biconical antenna. One such manufacturer is Tecom Industries Inc. Their biconical antennas include part numbers 201093, 201464 and 201125. It is not believed that these antennas do not have any of the unique features described herein.
Three important characteristics of a biconical antenna are its input impedance, beam characteristics in the elevation plane, and the flatness of its gain as a function of frequency. With conventional biconical antennas, a system specification cannot be met that includes all three of these parameters. For example, the conventional biconical antenna has only three parameters that can be adjusted: the upper and lower cone angles, .theta..sub.1 and .theta..sub.2 and the length of the upper and lower cones, R.sub.1 and R.sub.2. Once the angles .theta..sub.1 and .theta..sub.2 have been determined, the antenna input impedance is set. Since the beam characteristics and gain flatness are both influenced by R.sub.1 and R.sub.2, it is impossible to adjust both independently.
Therefore, it is an objective of the present invention to provide for an improved high-power, shaped-beam, ultra-wideband biconical antenna that permits flexible adjustment of its operating characteristics.